A common feature in mobile communication devices, such as cellular telephones, is a contacts database or address book application in which users can store the names and phone numbers (as well as other information) of individual and business contacts. Another common feature is functionality which receives the telephone number of an incoming call, which is provided as part of the call initiation protocol, and uses that number to look up a contact data record. If a match of the incoming phone number is found within the contact database, the mobile device can display the name and/or image of the caller using information stored in the corresponding contact data record. Such functionality is very popular since it allows mobile device users to know who is calling without having to memorize the phone numbers of their friends and contacts. However, this functionality is only available if the caller is calling from a phone number stored in the contact database. If a caller borrows the phone from another person or changes telephones, this functionality is defeated because the telephone number will not be recognized or will be recognized as that of a different contact.